Nanotechnology to Nanotoxicology, from page 25 waters from wastewater discharge. (85) (5)(6)(7)(8)(9) Nanoparticles are already in our soil and wastewater.
Beneficial Bacteria at Risk: Antibacterials Gone Awry
While we need antibacterial products in medicine, too much of a good thing can cause disruption in healthy ecosystems including our gastrointestinal tract. Studies have now shown that E. Coli bacteria strains were greatly inhibited by even small amounts of titanium dioxide nanoparticles. Most of these are beneficial friendly bacteria that keep the gut healthy by preventing establishment of pathogenic bacteria and producing vitamin K. Titanium dioxide particles have been considered non-toxic, as they do not incite a chemical reaction. Nanoparticles of titanium, however, interact with living organisms in a much different way. They can travel through the body and cause oxidative stress. Schiestl exposed mice to titanium dioxide in their drinking water. By the fifth day, they began to show genetic damage with double stranded DNA breaks and signs of inflammation. (76) Silver has broad spectrum antimicrobial activity towards many pathogens and it has been used in the past for medicinal purposes. The bactericidal activity of silver, however, inhibits soil microbial growth at levels below the concentrations of other heavy metals. (77) The antimicrobial effects of silver nanoparticles also have impacts at the ecosystem level affecting beneficial soil organisms (bacteria and fungi) that “feed” nutrients to plants. Researchers grew plants in biosolids with and without the addition of ecologically relevant silver nanoparticles. These levels of silver nanoparticles were within the range that the U.S. Environmental Protection Agency reported finding in a recent survey of biosolids from water treatment plants. The nanoparticles reduced the growth of one of the tested plant species by 22 % compared to silver-free biosolid treatment. Similarly, microbial biomass was reduced by 20%. (80) Considering nanoparticles do not degrade, are biologically active, and bioaccumulate, this has serious implications for the future of agriculture. Canada, in 2010, joined several other countries banning nanotechnology as a prohibited substance or method in organic food production. (81)
Hijacking Wastewater Treatment
Sewage treatment is a several step process of removing contaminants from wastewater prior to discharge into local waterways or for non-potable uses. In southern California, sewage effluent is used as drinking water after additional treatments. Usually, there are three steps. Primary treatment involves separating solids from liquids. Secondary treatment involves biological degradation of the suspended organic matter in the effluent by microorganisms. Tertiary treatment occurs when additives are used to clean the water if discharged into a sensitive ecosystem or if used for non-potable uses, such as golf courses. Nanoparticles have been shown to inhibit bacteria that are used to help degrade the organic matter in sewage treatment plants. (88)(89) Preliminary studies to evaluate removal of nanoparticles in wastewater
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show that it is not as easy as predicted. (83)(84) Dr. Limbach states “results indicate a limited capability of the biological treatment step to completely remove oxide nanoparticles from wastewater.” (83) Next Steps in Growing a Sustainable Nanotechnology Industry While there has been an avalanche of research and development in commercial nanotechnology, there has been a sharply contrasted lack of data with regards to human and environmental safety testing. The emerging science of nanotoxicology has identified some real concerns for some nanoparticles with regards to public health and the environment, including wildlife, fragile aquatic, and soil ecosystems. “The current state of oversight regimes should raise serious concerns for policymakers tasked with the challenge of encouraging nanotechnology innovation in a responsible and sustainable manner,” says David Rejeski, Director, Project on Emerging Nanotechnologies, Woodrow Wilson International Center for Scholars. Many government and non-governmental organizations have written extensive reports with regards to the concerns of nanotechnology and its oversight. The conclusion of these reports is that there is inadequate data on toxicology of these diverse particles, exposure data, and biomonitoring, as well as a lack of adequate regulation. A comprehensive 2011 report by the Office of Environmental Health Hazard Assessment Cal/EPA and the University of California San Francisco titled “Recommendations for Addressing Potential Health Risks From Nanomaterials” discusses these issues, and specific goals for government agencies were suggested. (1) Many lessons have been learned about chemical contamination too late. It is hoped that earlier action will prevent major public and environmental health problems. Below are some policy recommendations from the report.
UCSF-OEHHA Recommendations for Addressing Potential Health Risks From Nanomaterials
1. Traditional mass-based dose models may not be sufficient to characterize toxicity. New traits or properties will need to be defined and considered. 2. Heeding early warnings and using environmental monitoring is integral to identifying, evaluating, and monitoring potential hazards. 3. Persistent and/or bioaccumulative materials should be identified early, as build-up of exogenous chemicals are usually detrimental in some way. 4. Targeted research in the area of biological transport and distribution of nanomaterials, including sources, routes of contact, and internal distributions. Integrate this with the information gathered on exposure potential. 5. Require sufficient toxicological testing information to assess safety of risks to consumers, including susceptible subpopulations such as infants preferable premarket, and postmarket as necessary. 6. Require testing of release and exposure potential for nanomaterials in consumer products that have widespread